Soluble Expression of Small Antibody Fragments against PD-L1 Using Escherichia coli with High Yield and Purity

Abstract

Programmed death-ligand 1 (PD-L1) is a surface protein overexpressed in tumor cells. Recently, targeted therapy using PD-L1 antibodies to reconstitute the antitumor activity of T cells has received considerable attention as a cancer treatment. Among the several types of anti-PD-L1 antibodies, small-sized antibody fragments are useful agents to block PD-L1 for experimental and therapeutic purposes owing to their high penetration efficacy toward dense tumor cells. Herein, we expressed and purified recombinant single chain fragment of variable domain, variable heavy chain, and variable light chain, against PD-L1 in a soluble form using Escherichia coli, resulting in their high yield and high purity. We confirmed the antigen-binding efficiency of these antibody fragments, which showed antigen concentration-dependent responses. These results suggest that these small antibody fragments can serve as new agents for blocking or detecting PD-L1.